These rules have a graduated slide that extends up to a full 6 inches. The slide runs under friction in a T slot and has a stop at each end so slide will not fall out. Marked both sides and both edges to 1/16ths of an inch, 16 inch stud centers in red, regular outside markings. 5/8" wide.

Eliminates figuring and chance of error when working with 45° elbows. It is graduated on one side, in black, consecutive inches to 16ths, both edges. Other side in red, 45° scale inches to 16ths, upper edge only. Turning rule from black to red gives, at a direct reading, the corresponding 45° elbow measurement.